When mineralized tissue (e.g., bone) is damaged as a result of injury or disease, it is often necessary to provide an implant or graft to facilitate healing or preventing further damage. Natural or synthetic bone graft materials (such as hydroxyapatite) have been used in mineralized tissue repair (such as orthopedic or dental surgery). See, e.g., U.S. Pat. Nos. 6,846,853 and 7,381,224. There is a continuing need for improved bone graft materials. To securely affix the materials to target sites, flexibility, compression modulus and directional self-expandable properties are important considerations.